An antenna switch is a device to route radio frequency (RF) signal from one input to multiple output paths. The RF signal can be a signal having a relatively large swing. The antenna switch is a first transistor stage of a cellular RF front-end module. For an antenna switch for the third generation (3G) or fourth generation (4G) application, the requirement for harmonic rejection is relatively strict. For example, when an input RF power of the RF signal is 33 dBm, the second harmonics caused by the antenna switch should be lower than −70 dBm.